The long-term objective is to develop and test a new theory concerning the control of behaviors that are regularly elicited by reinforcing events in that environment. The elicitation process may be described as a poisson-emitter type of pacemaker-accumulator system, one whose rate constant is proportional to the rate of reinforcement in the environment. This conceptualization, or variants of it (e.g., normal approximations, or recurrent processes with error in the accumulator as well as the pacemaker), permits specific predictions to be made in numerous conditioning situations. The assumption of proportionality between the rate of the internal clock (pacemaker) and rate of reinforcement is a rad- ical one. It has implications for mental health issues in that it entails a fundamental reorientation of our notions about how reinforcement and punishment controls behavior. For instance, the delay of reinforcement gradient will not be a constant, but will become steeper in richer environments. We will evaluate the theory both against extant data, and against numerous proposed experi- ments. These address the issues of the mediating role of adjunctive behavior in the estimation of time, of the variation in the speed of the pacemaker with the richness of the environment, of the context over which the speed of the pacemaker is normalized, and of alternate mechanisms that may mediate the fine-scale judgments of time. The experiments will typically be psychophysical conditioning experiments with non-human subjects (rats and pigeons), and will serve both to test specific predictions, and to evaluate tentative extensions of the theory to behavioral and incentive contrast, rate laws, and choice of delayed reinforcers.